The foundation models run on the device for access to the local graph database and to interact with local actions (intents).
Not everything runs locally, but a local model still needs to run to understand that it needs to recruit help, to package up a subset of data for the external agent, and to perform actions on its behalf as well as return results.
Without the local agent, you are shuttling off all your data to be persisted by an AI cloud provider in case they need it.